Recovery of poly(arylene sulfide ketone) and poly(arylene sulfide diketone) resins

ABSTRACT

A poly(arylene sulfide ketone) or poly(arylene sulfide diketone) resin having improved handling characteristics is prepared by a process comprising preparing in a first enclosed vessel a slurry comprising a solid poly(arylene sulfide ketone) or poly(arylene sulfide diketone) resin and a liquid polar organic compound, and optionally water; then substantially liquifying the resin to form a mixture comprising substantially liquified resin and polar organic compound; then flashing the mixture into a second vessel having a pressure lower than the first vessel, thereby removing a portion of the polar organic compound and solidifying the resin. 
     When the slurry further comprises water, the invention method optionally includes a venting step prior to the substantial liquification of the resin and/or a concentration step after the substantial liquification of the resin.

FIELD OF THE INVENTION

This invention relates to processes for the production and recovery ofpoly(arylene sulfide ketone)s or poly(arylene sulfide diketone)s.

BACKGROUND OF THE INVENTION

Poly(arylene sulfide ketone), henceforth abbreviated as PASK, andpoly(arylene sulfide diketone), henceforth abbreviated as PASDK, resinsare engineering thermoplastics of potential commercial interest forfilm, fiber, molding, and/or composite applications because of theiroutstanding thermal and mechanical properties. General processes for theproduction of PASK and PASDK are known in the art. For example, PASK andPASDK can be prepared by the reaction of an alkali metal sulfide in apolar organic compound with a polyhaloaromatic ketone or apolyhaloaromatic diketone, respectively.

Disadvantages often associated with the production of PASK and PASDKresins pertain to the recovery and handling of the polymer produced.Specifically, at the completion of a typical polymerization reaction,the reaction mixture is generally in the form of a slurry comprising aliquid phase (e.g., predominantly a polar organic compound and water)and a particulate phase (e.g., predominantly polymeric resin andby-product salts), wherein the polymeric resin when recovered is in theform of powder-like particles. These powder-like particles generallyhave bulk densities of less than about 10 lbs/ft³ when recovered. Theslurry containing this extremely fine powder-like resin filters veryslowly and, thus, hampers the polymer's washability, recoverability andprocessability. Washing, recovering and/or processing PASK and PASDKresins, which have low bulk densities, are extremely difficult.

While a technique which increases the resin's bulk density could beadvantageous to the commercial industry by improving the resin'shandling, there are, however, some applications where such a techniquewould not be the most preferred mode for improving handling procedures.Specifically, in some commercial applications, it is necessary to havethe PASK or PASDK resin in theform of a fine powder. Examples of suchcommercial applications include, but are not limited to, powder coating,slurry coating and some types of compounding operations.

If a technique were employed which improved handling procedures byincreasing the bulk density of the PASK or PASDK resins, and if theseresins were to be employed in a process requiring the polymer to be inthe form of a powder, the resulting resin might have to be milled orground. Therefore, in those applications wherein it is desirable to usePASK or PASDK resins while in a powder form, it would be advantageous toimprove the handling of the respective resins while not increasing theirbulk densities.

A PASK or PASDK resin should be relatively free from metal halide saltsand other ash-producing contaminants to be of full usefulness and value.Another problem in the production of PASK and PASDK resins has been theseparation of high purity polymer from the contaminants in itspolymerization reaction slurry. The polar organic compounds generallyused in polymerization processes often cause difficulty in separatingthe polymer from its reaction mixture slurry by such usual means asfiltration since the liquid component and the polymer often produce afilter cake of such "pasty" physical characteristics that plugging ofthe filter is a continuous problem and washing the filter cake free ofother contaminants is difficult.

To avoid these problems, methods have been proposed for removal of thenon-polymeric liquid component from the polymer slurry before separationof the polymer and other contaminants is attempted. One such method isthe rapid, reduced-pressure evaporation of the non-polymeric liquidcomponent, often called a "flash-recovery" process. Generally, in aflash-recovery process, the polymerization mixture comprising thepolymer product, a polar organic compound and water, is at asuperatmospheric pressure and at a temperature which is greater than theatmospheric boiling points of most non-polymeric liquids presenttherein. This polymerization mixture is then transported across a "flashvalve". This rapidly reduces the pressure exerted on the mixture andresults in the vaporization of essentially all non-polymeric liquidscontained therein while simultaneously solidifying the polymeric liquidsin the form of a particulate resin.

STATEMENT OF THE INVENTION

One object of this invention is to provide a method for preparing lowbulk density polymers having associated therewith improved recovery andhandling procedures.

The PASK or PASDK resin recovered by this inventive process hasassociated therewith improved handling.

In accordance with one embodiment of this invention, novel PASK or PASDKresins are provided by a process comprising the steps of: (a) preparingin a first enclosed vessel a first slurry, wherein the solid componentthereof comprises a first particulate resin selected from the groupconsisting of PASK and PASDK, and wherein the liquid component thereofcomprises a polar organic compound and water; (b) substantiallyliquifying the first particulate resin contained in the first slurry toform a first mixture which comprises the substantially liquified resinand the polar organic compound and water; (c) subjecting the firstmixture to a concentration step to evaporate at least a portion of thewater and the polar organic compound contained therein to form a secondmixture; and (d) flashing the second mixture into a second vessel,wherein the internal pressure of the second vessel is substantiallylower than that of the first enclosed vessel containing the heatedliquid mixture, thereby removing essentially all of the remaining waterand a portion of the polar organic compound therefrom and simultaneouslysolidifying the substantially liquified resin to form a novel secondparticulate PASK or PASDK resin.

In accordance with another embodiment of this invention, novel PASK orPASDK resins are provided by a process comprising the steps of: (a)preparing in a first enclosed vessel a first slurry, wherein the solidcomponent thereof comprises a first particulate resin selected from thegroup consisting of PASK and PASDK, and wherein the liquid componentthereof comprises a polar organic compound; (b) substantially liquifyingthe first particulate resin contained in the first slurry to form afirst mixture which comprises the substantially liquified resin and thepolar organic compound; and (c) flashing the first mixture into a secondvessel, wherein the internal pressure of the second vessel issubstantially lower than that of the first enclosed vessel containingthe heated mixture, thereby removing a portion of the polar organiccompound therefrom and simultaneously solidifying the substantiallyliquified resin to form a novel second particulate PASK OR PASDK resin.

In accordance with yet another embodiment of this invention, novel PASKor PASDK resins are provided by a process comprising the steps of: (a)preparing in a first enclosed vessel a first slurry heated to atemperature of at least about 100° C. (212° F.), wherein the solidcomponent thereof comprises a first particualte resin selected from thegroup consisting of PASK and PASDK, and wherein the liquid componentthereof comprises a polar organic compound and water; (b) venting vaporsfrom the enclosed first vessel containing the heated first slurry,thereby removing at least a portion of the water therefrom; (c)substantially liquifying the first particulate resin contained in thefirst slurry to form a first mixture which comprises the substantiallyliquified resin and the polar organic compound; and (d) flashing thefirst mixture into a second vessel, wherein the internal pressure of thesecond vessel is substantially lower than that of the first enclosedvessel containing the heated mixture, thereby removing a portion of thepolar organic compound therefrom and simultaneously solidifying thesubstantially liquified resin to form a novel second particulate PASK orPASDK resin.

When practicing any of the embodiments of this invention, the handlingof the novel second particulate resin is significantly improved overthat of the first particulate resin.

DETAILED DESCRIPTION OF THE INVENTION

As used herein, the term "bulk density" refers to the density of a dry,particulate resin. A resin's bulk density is determined herein bycompletely filling a container, having a known weight and volume, to itsbrim with a dried sample of the polymer to be tested. The bulk densityof the specific polymer is then calculated by dividing the weight of thepolymer in pounds (lbs) by the volume of the container in cubic feet(ft³). The bulk density of resin formed in typical PASK and PASDKpolymerization processes is often less than about 10 lbs/ft³.

Bulk density of dry, particulate resins can be determined in terms of"loose" bulk density and/or "compacted" bulk density. The loose bulkdensity of a dried granular polymeric resin is determined by measuringthe weight of the polymer as it naturally fills the test container toits brim by gravity. On the other hand, the compacted bulk density of adry, particulate resin is determined by physically compacting thepolymer in the test container, until the compacted polymer reaches thebrim thereof, prior to weighing the amount of polymer contained therein.When the term "bulk density" is used herein, it refers to the resin'sloose bulk density.

The polymers which are treated by the process of this invention arethose having the repeating unit: ##STR1## n=0 or 1, Z=divalent radicalselected from ##STR2## m=0 or 1, A is selected from ##STR3## and R ishydrogen or an alkyl radical having 1-4 carbon atoms.

Although other polymeric resins are not excluded, in general, thepresently preferred PASK resins produced and/or recovered by theinventive process disclosed herein are poly(phenylene sulfide ketone)resins (PPSK) having as the repeating unit: ##STR4##

In general, the preferred PASDK resins produced and/or recovered by theinventive process herein are poly(phenylene sulfide diketone) resins(PPSDK) having as the repeating unit ##STR5##

When practicing the embodiments of this invention, if desired, the novelsecond particulate resin can thereafter be separated, washed, andoptionally dried in accordance with known techniques.

When employing any of the embodiments of this invention, the handling ofthe novel second particulate resin is significantly improved over thatof its respective first particulate resin.

Since this invention can be practiced at any time after a firstparticulate PASK or PASDK resin is formed, it can be viewed as either(1) an effective means for improving the handling of PASK or PASDKresins without materially increasing the resin' respective bulkdensities, or (2) a means for providing novel low bulk density PASK orPASDK resins which have associated therewith improved handling.

When practicing this invention, a first slurry is prepared, wherein thesolid component thereof comprises a first particulate resin selectedfrom the group consisting of PASK and PASDK, and wherein the liquidcomponent thereof comprises a polar organic compound. Any suitablemethod can be employed to prepare the first slurry of this invention.

An example of a suitable method which will produce such a first slurryis one wherein a polyhalo-substituted aromatic ketone or diketone iscontacted, under suitable polymerization conditions, with reactantscomprising: (a) a sulfur source; (b) a polar organic compound; and (c)water. Under these conditions, a first slurry results, wherein the solidcomponent thereof comprises a first particulate PASK or PASDK resin(having a bulk density generally less than about 10 lbs/ft³ whenrecovered and dried), and wherein the liquid component thereof comprisesthe polar organic compound and water.

Another example of a suitable method which results in such a firstslurry comprises taking a PASK or PASDK resin which has already beenprepared, recovered, and optionally dried, and adding this resin to aliquid comprising a polar organic compound and, optionally, water.

If certain embodiments of this invention are being practiced, the liquidcomponent of the first slurry will also comprise water. For oneembodiment of this invention, the first slurry is heated to atemperature of at least about 100° C. (212° F.), preferably at leastabout 200° C. (392° F.). Any suitable method can be employed to preparethis heated first slurry. One example of a suitable method which willproduce such a heated first slurry is the polymerization process recitedabove. Another example of a suitable method which results in such aheated first slurry comprises taking a PASK or PASDK resin which hasalready been prepared, recovered, and optionally dried and adding thisresin to a liquid mixture comprising a polar organic compound and water.This slurry is then heated, while in an enclosed vessel, to atemperature of at least about 100° C. (212° F.), preferably at leastabout 200° C. (392° F.).

When practicing this invention, the molar ratio in the first slurry ofthe moles of polar organic compound per moles of divalent sulfur presentin the first particulate resin is generally determined by mechanicaland/or economic limitations. If the first slurry is that resulting froma polymerization reaction, the molar ratio of the moles of polar organiccompound to the moles of divalent sulfur employed as a reactant rangesfrom about 3:1 to about 25:1; more preferably, from about 6:1 to about20:1; and even more preferably, from about 8:1 to about 16:1.

Polar organic compounds which can be employed when practicing thisinvention are those which remain substantially in a liquid phase at thetemperatures and pressures used for liquifying the first particulateresin. Moreover, these polar organic compounds should preferably alsofunction as a solvent of the first particulate resin. Generally, organicamides are employed as the polar organic compounds. Suitable organicamides can be cyclic or acyclic and can have from 1 to about 10 carbonatoms per molecule. Examples of suitable organic amides includeformamide, acetamide, N-methylformamide, N,N-dimethylformamide,N,N-dimethylacetamide, N-ethylpropionamide, N,N-dipropylbutyramide,2-pyrrolidone, N-methyl-2-pyrrolidone (NMP),N,N'-ethylenedi-2-pyrrolidone, hexamethylphosphoramide, tetramethylurea,1,3-dimethyl-2-imidazolidinone and mixtures thereof. NMP is thepresently preferred organic amide.

PASK and PASDK resin polymerizations generally employ polymerizationtemperatures ranging from about 232° C. (450° F.) to about 288° C. (550°F.). At the termination of typical PASK or PASDK polymerizationreactions, a heated first slurry is generally formed. This heated firstslurry comprises a particulate PASK or PASDK resin as the solidcomponent and a mixture containing predominantly a polar organiccompound and water as the liquid component. At the termination of thepolymerization, the reactor pressure will generally range from about 200psig to about 500 psig.

Substantial liquification of the first particulate PASK or PASDK resincontained in the first slurry can be accomplished by using any suitableliquification process known by those skilled in the art. One example ofsuch a suitable liquification process is heating the slurry to atemperature at which the first particulate resin liquifies. It is noted,however, that since the liquid component of the slurry containing theresin generally comprises a polar organic compound which can alsofunction as solvent for the first particulate resin, the elevatedtemperature of the aforementioned resin liquification process willgenerally not exceed the melting point of the first particulate resin.For example, if the solid component of a slurry comprises, as the firstparticulate resin, poly(phenylene sulfide ketone) (PPSK), and the liquidcomponent of the same slurry consists essentially of the polar organiccompound, NMP, in order to liquify this particulate resin, this slurrymust be heated to a temperature of at least about 280° C. (536° F.),which does not exceed the melting temperature of PPSK (about 340° C.).

Another example of a suitable liquification process is the addition of asuitable compound which can function as a solvent of the particulateresin. Depending upon the type and/or amount of this compound beingsubsequently added to the first slurry and the characteristics of thefirst particulate resin, it may still be necessary to elevate thetemperature of the first slurry in order to liquify the firstparticulate resin contained therein. Moreover, if other liquidcomponents are present in the first slurry, the temperature needed tosubstantially liquify the first particulate PASK or PASDK resincontained therein generally increases. For example, if the solidcomponent of a slurry comprises as the first particulate resin PPSK andthe liquid component of the same slurry consists essentially of thepolar organic compound, NMP, and a small amount of water (e.g.,approximately 10% by weight of liquid component), in order to liquifythis specific particulate resin, this slurry must be heated to atemperature of at least about 300° C. (572° F.).

In one embodiment of this invention, prior to the substantialliquification of the resin, the enclosed vessel containing the heatedfirst slurry is vented, such that at least a portion of the water isremoved therefrom. In order to practice this technique, the temperatureof the first slurry must be above about 100° C. (212° F.), preferablyabove about 200° C. (392° F.). After the enclosed vessel has beenvented, the liquid component of this vented first slurry ispredominantly polar organic compound. Thereafter the resin issubstantially liquified, often at a lower temperature and/or pressurethan if the venting step had not been employed.

For example, if the first particulate resin contained in the ventedfirst slurry is PPSK, and if the polar organic compound is NMP, the PPSKresin generally can be substantially liquified by heating the ventedslurry to a temperature of at least about 280° C. (536° F.), preferably,from about 280° C. (536° F.) to about 350° C. (662° F.), and morepreferably, from about 290° C. (554° F.) to about 300° C. (572° F.).

After the first particulate PASK or PASDK resin has been substantiallyliquified, the non-polymeric liquid components are separated from thepolymeric liquid components of the first mixture. In accordance withthis invention, the separation of the substantially liquified resin iseffectuated by a process referred to as "flash-recovery".

The separation of the non-polymeric liquid components from the polymericliquid component can be effectuated in either a one-stage or a two-stageflash-recovery process.

In the one-stage flash-recovery process the heated first mixture, whichis at a superatmospheric pressure, is transferred across a flash valveto a vessel maintained at pressure signficantly lower than the specificsuperatmospheric pressure. This results in a rapid decrease in pressureexerted on the heated mixture. This rapid decrease in pressure resultsin vaporizing a portion of the non-polymeric liquid components whilesimultaneously solidifying essentially all of the polymeric liquidcomponents. The resulting novel second particulate resin is generally inthe form of a feathery material.

In the two-stage flash-recovery process, the heated liquid mixture whichis at a superatmospheric pressure is first concentrated by ventingvapors therefrom, such that a portion of the non-polymeric liquidcomponents vaporize and are thereafter removed therefrom. Thisconcentration step is preferably employed when water is one of thenon-polymeric liquid components present in the first mixture. If wateris present, the concentration step is preferably conducted untilessentially all of the water is removed therefrom. After theconcentration step, a major portion of the resin should still be in aliquid phase. If not, the resin should be substantially liquified priorto proceeding to the next step of this process. After the concentrationstep, the remaining mixture is transferred across a flash valve to avessel maintained at a pressure significantly lower than the pressureexerted on the concentrated mixture.

While the conditions employed in the concentration step of the two-stageflash-recovery process can vary, the pressure during this step willgenerally be above atmospheric pressure. However, sub-atmosphericpressure operation is to be considered as within the scope of thisinvention. The pressure reduction during the concentration step shouldbe sufficient to evaporate essentially all of the water, if present, andat least a portion of the polar organic compound present. Generally, thepressure reduction should be such that at least one-third of the polarorganic compound present vaporizes; preferably, such that at leastone-half of that present vaporizes.

When employing either the one- or two-stage flash-recovery processrecited above, the atmospheric pressure of vessel into which the mixtureis flashed must be lower than the pressure of the vessel containing themixture. This pressure difference can vary depending upon (1) the amountand characteristics of the specific polymeric and non-polymeric liquidcomponents of the mixture and (2) the amount and/or type ofnon-polymeric liquid component(s) desired to be removed from themixture.

Generally, the pressure of the vessel into which the heated mixture isflashed is from about 20 to about 100 percent, preferably, from about 50to about 95 percent less than that of the vessel containing the liquidmixture. For example, under typical operating conditions, the internalpressure of the vessel containing the mixture ranges from about 75 toabout 500 psia, preferably, from about 100 to about 300 psia. Underthese conditions, the internal pressure of the vessel into which themixture is flashed ranges from about 1 to about 60 psia, preferably,from about 10 to about 30 psia.

The operation of this invention can best be understood by reference tothe drawing which shows a method for recovering a novel secondparticulate PASK and PASDK resin from a heated first slurry, wherein theliquid component comprises a polar organic compound and water, byemploying the two-stage flash-recovery process. The drawing will bedescribed in terms of the recovery of PPSK, however, the processillustrated therein can easily be adapted to PASK or PASDK by those ofordinary skill in the art.

In FIG. 1, sodium hydroxide, sodium hydrosulfide, N-methyl-2-pyrrolidone(NMP) and water are charged into reactor 3 through line 1. Thepolyhaloaromatic compound 4,4' dichlorobenzophenone is charged intoreactor 3 through line 2. The contents of reactor 3 are subject to anelevated temperature of about 250° C. (482° F.) and an elevated pressurein the range from about 100 psig to about 120 psig to produce apolymerization reaction slurry wherein the solid component thereofcomprises a first particulate PPSK resin and salt by-products, andwherein the liquid component thereof comprises NMP, water, by-productalkali metal halide, and other impurities.

At the end of the polymerization, the concentration step can be carriedout. If desired, the concentration step can be conducted in the samevessel by supplying the necessary heat input through coil 5 and drivingoff water and NMP through line 6. This concentration step is continueduntil essentially all of the water and preferably up to about 50% of theNMP is removed from the liquid mixture.

After the concentration step, reactor 3 is sealed and thereafter heatedby coil 5 to an elevated temperature of at least about 280° C. (536° F.)to form a predominantly liquid mixture comprising substantiallyliquified PPSK resin and NMP. The liquid mixture in reactor 3 is removedtherefrom through line 7 to flash vessel 8 through a flash valve. Themixture from reactor 3, which is at a superatmospheric pressure, isflashed into vessel 8 to approximately atmospheric pressure. Thisflashing process results in the vaporization and removal of a portion ofthe non-polymeric liquid components, while simultaneously solidifyingthe polymeric liquid component. The vaporized non-polymeric liquidcomponents are removed from vessel 8 through line 11.

The particulate material remaining in flash vessel 8, which comprisesthe novel PPSK resin, by-product alkali metal halide and otherimpurities, is removed therefrom through line 10 for washing and otherdownstream processes. The vaporized NMP, removed from vessel 8 throughline 9 and/or from reactor 3 through line 6, can be processed to removewater and other impurities therefrom and made ready for return toreactor 3.

Still in reference to FIG. 1, another method of performing the abovetwo-stage flash-recovery process is by employing the concentration stepafter the particulate PPSK resin is substantially liquified.Specifically, after the polymerization slurry is prepared, reactor 3 isheated, while sealed, to a temperature of at least about 300° C. (572°F.) with coil 5 to form a predominantly liquid mixture comprising NMP,water, and substantially liquified PPSK resin. This mixture is thenconcentrated by venting vapors from reactor 3 through line 6. As above,this concentration step is continued until essentially all of the waterand, preferably, up to about 50% of the NMP is removed from the mixture.After the concentration step, the PPSK resin should still be in asubstantially liquified form. If a major portion of the PPSK resinbegins to solidify, additional heat is applied by coil 5 until the resinis again substantially liquified. The concentrated mixture, which is ata superatmospheric pressure, is then removed from reactor 3 through line7 to flash vessel 8 as described above, to result in a particulatematerial comprising the novel PPSK resin.

The thermal stability and processability of the resulting novel secondparticulate resin prepared in accordance with this invention can beimproved by subjecting the novel second particulate resin to a caustictreating process. This subsequent treating process is conducted at anelevated temperature with a suitable base, such as an alkali metalcarbonate or an alkali metal hydroxide.

Another means of improving the thermal stability and processability ofthe resulting novel second particulate resin, is by treating theresulting novel second particulate resin at an elevated temperature,with water-soluble calcium cations. The process of subsequently treatingthe resulting novel second particulate resin with either a base or thecalcium cations or both can be carried out with conventional equipment.A convenient method for carrying out a subsequent treating procedure isto first recover the novel second particulate resin from the secondslurry. The recovered novel second particulate resin is then contactedwith the base and/or the calcium cations, in any sequence, in anenclosed vessel which has provided therein a means of agitation. Thiscontacting can be carried out in a single vessel or in a plurality ofvessels.

EXAMPLES

The examples which follow are intended to assist in a furtherunderstanding of this invention. Particular materials employed, species,and conditions are intended to be illustrative of the invention and arenot meant to limit the reasonable scope thereof.

EXAMPLE I

This example demonstrates one embodiment of this invention. The PASKresin used in this example was poly(phenylene sulfide ketone),henceforth PPSK.

The PPSK used in this example was prepared by reacting, in a stirred2-gallon reaction vessel, the following reagents which were previouslydeoxygenated by three pressurize-release cycles using nitrogen: 504grams (2.0 moles) of the monomer 4,4'-dichlorobenzophenone (4,4'-DCBP),192 grams of a 58.3 weight-% sodium hydrosulfide (NaHS) solution (i.e.,112 grams (2.0 moles) NaHS and 80 grams (4.4 moles) water), 80 grams(2.0 moles) of sodium hydroxide (NaOH), 2400 ml (24.86 moles) ofN-methyl-2-pyrrolidone (NMP), and 108 ml (6.0 moles) of water, at 250°C. for approximately 3 hours.

During the three hour polymerization period, a first slurry was producedwherein the solid component was predominantly particulate PPSK (althougha certain amount of NaCl was also present) and the liquid component waspredominantly a mixture of NMP and water. The temperature of the firstslurry at this point was approximately 250° C.

The particulate PPSK was then substantially liquified by heating theslurry to 300° C. while increasing the mixer speed. The internalpressure of the reactor at 300° C. was approximately 380 psig.

After liquification of the particulate PPSK resin, the mixture waspermitted to flash to atmospheric pressure. This flashing process wasaccomplished by quickly pressurizing the mixture in the reaction vesselthrough an induction tube and a control valve into a 1000 ml flashingcylinder maintained at atmospheric pressure. The flashing processresulted in the solidification of the substantially liquified resin. Theparticulate resin collected in the flashing cylinder after the flashingprocess is hereinafter referred to as Resin 1. After removing Resin 1from the flashing cylinder, the resin was washed by being slurried withapproximately one gallon of water and then filtered. The water wasfiltered from the slurry containing Resin 1 in less than 1 minute.

For the purpose of further demonstrating the effectiveness of thepresent invention, four additional PPSK resins (Resins 2-5, inclusive)were prepared.

Resin 2 was prepared in substantially the same manner as Resin 1. Resins3 through 5 were prepared in the same manner as Resins 1 and 2, with themodification that the polymerization reactor during the preparation ofResins 3 and 5 was vented at 250° C. prior to heating the slurry to 300°C. Properties of Resins 1-5 are listed in Table I.

For comparison, two polymeric samples (Resins 6 and 7) were preparedusing a polymerization process which did not include a flash-recoverystep. The means employed for recovering Resins 6 and 7 from thecompleted polymerization reaction mixture is referred to as a"liquid-quench" recovery process. Both Resins 6 and 7 were initiallyprepared in substantially the same manner as Resin 1.

The recovery of Resins 6 and 7 from their respective polymerizationreaction mixtures consisted of heating the reaction mixture slurry to atemperature of 300° C. while simultaneously increasing the stirrer speedto 500 rpm. After this temperature was obtained, 500 cc (27.8 moles) ofwater were charged into the respective reactors. Following the chargingof the water, the respective reactors were cooled to approximately roomtemperature. Opening these reactors revealed granular particles of PPSKwhich were subsequently recovered by filtration. The recovered granularPPSK resins were then washed with water and permitted to dry. Thisrecovered material is hereinafter referred to as Resins 6 and 7,respectively. The properties of Resins 6 and 7 are also given in TableI.

                  TABLE I                                                         ______________________________________                                        Comparison of Polymer Recovery Techniques                                     Resin               Recovery  Bulk Density.sup.(b)                            No.     Venting.sup.(a)                                                                           Technique (lbs/ft.sup.3)                                  ______________________________________                                        1       NO          FLASH     6.0                                             2       NO          FLASH     6.3                                             3       YES         FLASH     6.6                                             4       YES         FLASH     6.2                                             5       YES         FLASH     6.5                                             6       NO          QUENCH    19.8                                            7       YES         QUENCH    21.0                                            ______________________________________                                         .sup.(a) This column identifies those resins which were prepared by           employing a venting step at 250° C. prior to heating the slurry to     300° C.                                                                .sup.(b) This identifies the loose bulk densities of the resins.         

The data in Table I demonstrates that Resins 1-5, which were recoveredby the flash-recovery process, exhibited a much lower bulk density thansimilar resins recovered by the liquid quench recovery process (Resins 6and 7).

To illustrate the improvement in filtration rate realized by theutilization of the flash-recovery process, the following resin (Resin 8)was prepared using a recovery process other than the flash-recovery.

Resin 8 was prepared by reacting the following deoxygenated reagents ina stirred one-gallon reaction vessel: 502 grams (2.0 moles of themonomer 4,4'-DCBP, 192 grams of a 58.3 weight-% of NaHS solution (i.e.,112 grams (2.0 moles) NaHS and 80 grams (4.4 moles) water), 80 grams(2.0 moles) of NaOH, 2400 mL (24.86 moles) of NMP, and 108 grams (6.0moles) of water, at 250° C. for approximately 3.5 hours. During the 3.5hour polymerization period, a first slurry was produced wherein thesolid component was predominantly particulate PPSK and the liquidcomponent was predominantly a mixture of NMP and water. The temperatureof the first slurry at this point was approximately 250° C.

The particulate PPSK was then substantially liquified by heating theslurry to 305° C. After that temperature was reached, the contents ofthe reaction vessel were permitted to cool at a rate of approximately 1°C./minute. When the reactor and its contents had cooled to approximatelyroom temperature, a second slurry had been formed wherein the solidcomponent thereof comprised predominantly Resin 8.

Resin 8 was then separated from the liquid contents of a second slurry.Thereafter, Resin 8 was washed by being slurried with approximately onegallon of water and then filtered. The water was filtered from theslurry containing Resin 8 in about 5 minutes.

The above data demonstrates that the filtration rate observed whenemploying the flash-recovery process of this invention (less than oneminute) was significantly faster than if the inventive recovery processwere not employed (five minutes).

EXAMPLE 2

This Example demonstrates the use of the inventive recovery process on acommercial scale.

To a large, stirred reaction vessel was charged the followingdeoxygenated reagents: 84.9 pounds of 4,4'-DCBP, 28.07 pounds of a 47.1weight-% aqueous sodium hydroxide solution, 30.32 pounds of an aqueoussolution which was 58.80 weight percent NaHS and 0.30 weight-% sodiumsulfide, 0.53 pounds of sodium carbonate and 31.4 gallons of NMP. Thereaction vessel was then sealed and heated to approximately 249° C.(481° F.) and held there for approximately 2.5 hours. At this point, thepressure in the reaction vessel was increased 30 psig by the addition ofcarbon dioxide. The time required for the carbon dioxide addition andcontinued hold at 481° F. was 30 minutes.

The reactor was then heated to 287° C. (548° F.), at which point thereactor contents were transferred across a flash valve to separate theproduct polymer from most of the normally liquid components present.After the polymer recovery, which included washing and drying, a totalof 29 pounds of polymer was collected. Hereinafter, this polymer isreferred to as Resin 9.

To further illustrate the use of the inventive process on a largerscale, Resin 10 was prepared in the same general way as was Resin 9.Differences in the preparation of Resin 10 include the following: (a) atthe addition of the carbon dioxide with its total of 30 minutes additionand hold time, the reactor was vented over a period of 1 hour and 46minutes from a pressure of 210 psig to 75 psig. The reactor was thenheated to 550° F. and subjected to flash-recovery in the same manner aswas Resin 9. The total weight of Resin 10 which was recovered weighed49.5 pounds.

It is evident from the foregoing that various modifications can be madeto the embodiments of this invention without departing from the spiritand scope thereof, which will be apparent to those skilled in the art.Having thus described the invention, it is claimed as follows.

That which is claimed is:
 1. A process for preparing a particulatepolymeric resin, having improved handling, comprising the steps of:(a)preparing in an enclosed first vessel a first slurry comprised of asolid component and a liquid component, wherein the solid component ofsaid first slurry comprises a first particulate resin selected from thegroup consisting of poly(arylene sulfide ketone) and poly(arylenesulfide diketone) resin, and wherein the liquid component of said firstslurry comprises a polar organic compound and water; (b) substantiallyliquifying said first particulate resin contained in said first slurryto form a first mixture which comprises said substantially liquifiedresin and said polar organic compound and water; (c) subjecting saidfirst mixture to a concentration step to evaporate at least a portion ofsaid water and at least a portion of said polar organic compoundcontained in said first mixture, thus forming a concentrated secondmixture; and (d) flashing said second mixture into a second vessel,wherein the internal pressure of said second vessel is substantiallylower than that of said first enclosed vessel containing saidconcentrated second mixture, thereby removing essentially all of saidwater and a portion of said polar organic compound remaining therefromand simultaneously solidifying said substantially liquified resin toform a second particulate resin, wherein the handling of said secondparticulate resin is superior to the handling of said first particulateresin.
 2. A process in accordance with claim 1 wherein said firstparticulate resin comprises a poly(arylene sulfide ketone).
 3. A processin accordance with claim 2 wherein said substantial liquification ofsaid first particulate resin is accomplished by heating said firstslurry to a temperature of at least about 300° C.
 4. A process inaccordance with claim 3 wherein said substantial liquification of saidfirst particulate resin is accomplished by heating said first slurry toa temperature in the range from about 300° C. to about 325° C.
 5. Aprocess in accordance with claim 2 wherein said first slurry is preparedby reacting a polyhaloaromatic ketone, an alkali metal sulfide, waterand a polar organic compound under polymerization conditions.
 6. Aprocess in accordance with claim 5 wherein said polyhaloaromatic ketoneis a dihalobenzophenone; said alkali metal sulfide is sodium sulfide;and said polar organic compound is N-methyl-2-pyrrolidone.
 7. A processin accordance with claim 6 wherein said dihaloaromatic ketone is4,4'-dichlorobenzophenone.
 8. A process in accordance with claim 2wherein said poly(arylene sulfide ketone) is poly(phenylene sulfideketone).
 9. A process in accordance with claim 8 wherein said liquidcomponent of said second mixture consists essentially of said polarorganic compound and said substantially liquified resin.
 10. A processin accordance with claim 9 wherein said concentration of said firstmixture is accomplished by venting vapors from said enclosed firstvessel.
 11. A process in accordance with claim 1 wherein said firstparticulate resin comprises a poly(arylene sulfide diketone).
 12. Aprocess in accordance with claim 11 wherein said first slurry isprepared by reacting a polyhaloaromatic diketone, an alkali metalsulfide, water and a polar organic compound under polymerizationconditions.
 13. A process in accordance with claim 12 wherein saidpolyhaloaromatic ketone is a bischlorobenzoyl benzene; said alkali metalsulfide is sodium sulfide; and, said polar organic compound isN-methyl-2-pyrrolidone.
 14. A process in accordance with claim 11wherein said poly(arylene sulfide diketone) is poly(phenylene sulfidediketone).
 15. A process in accordance with claim 14 wherein said liquidcomponent of said second mixture consists essentially of said polarorganic compound and said substantially liquified resin.
 16. A processin accordance with claim 1 wherein, prior to substantially liquifyingsaid first particulate resin, the temperature of said first slurry isabove about 100° C.
 17. A process in accordance with claim 16 wherein,prior to substantially liquifying said first particulate resin, thetemperature of said first slurry is above about 200° C.
 18. A process inaccordance with claim 1 wherein said internal pressure of said secondvessel is about 50 to about 95% less than that of said first vessel. 19.A process in accordance with claim 1 wherein, immediately prior to step(d), said internal pressure of said first vessel ranges from about 75 toabout 500 psia, and wherein said internal pressure of said second vesselranges from about 1 to about 60 psia.
 20. A process in accordance withclaim 19 wherein, immediately prior to step (d), said internal pressureof said first vessel ranges from about 100 to about 300 psia, andwherein said internal pressure of said second vessel ranges from about10 to about 30 psia.
 21. A particulate polymeric resin, havingassociated therewith improved handling, prepared by a process comprisingthe steps of:(a) preparing in an enclosed first vessel a first slurry,wherein the solid component of said first slurry comprises a firstparticulate resin selected from the group consisting of poly(arylenesulfide ketone) and poly(arylene sulfide diketone) resins, and whereinthe liquid component of said first slurry comprises a polar organiccompound and water; (b) substantially liquifying said first particulateresin contained in said first slurry to form a first mixture whichcomprises said substantially liquified resin and said polar organiccompound and water; (c) subjecting said first mixture to a concentrationstep to evaporate at least a portion of said water contained in saidfirst mixture and form a heated second mixture; and (d) flashing saidsecond mixture into a second vessel, wherein the internal pressure ofsaid second vessel is substantially lower than that of said firstenclosed vessel containing said heated second mixture, thereby removingessentially all of said water and said polar organic compound remainingtherefrom and simultaneously solidifying said substantially liquifiedresin to form a second particulate resin, wherein the handling of saidsecond particulate resin is superior to the handling of said firstparticulate resin.
 22. A polymeric resin as in claim 21 wherein saidfirst particulate resin comprises a poly(arylene sulfide ketone).
 23. Apolymeric resin as in claim 21 wherein said first particulate resincomprises a poly(arylene sulfide diketone).
 24. A process in accordancewith claim 21 wherein said first slurry further comprises water.
 25. Apolymeric resin as in claim 21 wherein prior to step (b) said firstslurry is vented, removing at least a portion of said water therefrom.